Significant Impacts of Increasing Aridity on the Arid Soil Microbiome

Abstract

We identify key environmental and geochemical factors that shape the arid soil microbiome along aridity and vegetation gradients spanning over 300 km of the Atacama Desert, Chile. Decreasing average soil relative humidity and increasing temperature explain significant reductions in the diversity and connectivity of these desert soil microbial communities and lead to significant reductions in the abundance of key taxa typically associated with fertile soils. This finding is important because it suggests that predicted climate change-driven increases in aridity may compromise the capacity of the arid-soil microbiome to sustain necessary nutrient cycling and carbon sequestration functions as well as vegetative cover in desert ecosystems, which comprise one-third of the terrestrial biomes on Earth.

Assessing Microbial Community Patterns During Incipient Soil Formation From Basalt

“…Phylogenetic analysis of OTUs revealed Proteobacteria to be the dominant phylum in the system, an observation reported commonly for soils (Janssen, ) and seafloor basalts (Cockell et al, ; Orcutt et al, ; Singer et al, ). However, the surface samples more closely resembled oligotrophic community composition, with high relative abundance of Actinobacteria , as previously observed in other studies (Neilson et al, , ). Their filamentous growth may be important in weathering processes in miniLEO, as observed in invasion and colonization of basaltic glass by actinobacterial groups, with a predicted mechanism of multidirectional filamentous growth across the surface with branches invading pore spaces (Cockell et al, ), and abundance on veneers of rock surface (Ortiz et al, ).…”

A footprint of plant eco-geographic adaptation on the composition of the barley rhizosphere bacterial microbiota

“…The third observation is the marked enrichment of OTUs assigned to the phylum Actinobacteria in ‘Elite’ varieties when compared to members of the ‘Desert’ ecotype, in particular plants of the ‘Desert 2’ locations. At first glance, the ‘direction’ of this bacterial enrichment is difficult to reconcile with the eco-geographic adaptation of wild barleys and, in particular, the fact that Actinobacteria are more tolerant to arid conditions 34 and, consequently, more abundant in desert vs. non-desert soils 35 . However, the enrichment of Actinobacteria in modern crops compared to ancestral relatives has recently emerged as a distinctive feature of the microbiota of multiple plant species 36 .…”

Testing the two-step model of plant root microbiome acquisition under multiple plant species and soil sources

“…Additionally, natural variation in the climatic conditions was site-specific, while in the common garden experiment, tomato plants were watered regularly and climatic variation was minimized. The increased abundance of Actinobacteria in both soils and ruderal plants can also be a product of environmental water limitations, which directly affects the proportions of these phyla in arid soils, while humid sites usually have larger Proteobacteria abundances (Neilson et al, 2017). Proteobacteria have faster duplication times than Actinobacteria (Ramin & Allison, 2019).…”